Variable-impedance coil



Oct. 12 1926. 1,602,671

M. HENDERSON VARIABLE IMPEDANCE COIL Filed July 13. 1925 Mr Jaw/22w2/1711 aficaj fizzaemvzz Patented Oct. 12, 1926.

UNITED STATES MICHAS HENDERSON, OF JE'WEL, IOWA.

VARIABLE-IMPEDANCE COIL.

Application filed July 13, 1925. Serial No. 43,381.

The object of my invention is to provide a variable impedance, which maybe either inductive or non-inductive and which is simple, durable andinexpensive.

A further object is to provide an impedance which is uniformlyadjustable throughout its range and, therefore, does not have thedisadvantage of the usual impedance which is adjustable by steps.

Still a further object is to provide impedance coils, so wound that uponcompression, the coils thereof vill be shorted in proportion to theamount of compression, thereby reducing the impedance of the coils.

Still a further object is to provide a simple and efficient means foraccomplishing the compression of the impedance coils,

\Vith these and other objects in view, my invention consists in theconstruction, arrangen'icnt and combination of the various parts of mydevice, whereby the objects conten'iplated are attained, as hereinaftermore fully set forth, pointed out in my claim, and illustrated in theaccompanying drawings, in which Figure l is a top, plan view of myimpedance device.

Figure 2 is a side elevation of the same, showing the coils released.

Figure is an end elevation of the same, showing the co ls partlycompressed.

Figure -11; a diagrammatic view of my device and an electric n'iotorillustrating one way in wl ich it can be utilized.

In the accompanying drawing, I have used the reference numeral 10 toindicate generally, a core which can be made of soft cast iron or be oflaminated construction.

A base 11 may be provided on the lower, horizontal bar of the core forconvenience in fastening my device to a suitable support.

Pads 12 are formed on the core 10, and have on their upper surfaces,insulating Washers 13. The vertical bars of the core 10 have insulatingtubes 14 thereon.

A compressor bar 15 extends from one vertical bar to the other of thecore 10 and has holes 16 which are substantially the same size as theoutside diameter of the tubes 14.

It will thus be seen that the bar 15 is slidable vertically on the tubes14.

The bar 15 has its under surface insulated by the insulating strip 17. V

For adjus in; the compressor bar 15, I provide a red "18 journalled inthe m ner threaded boss and lower horizontal bars of the core 10, as at19 and 20. A flange 21 and a shoulder prevent endwise movement of therod 18.

A portion 23 of the rod 18 is screw thread ed, and coacts with aninternally screw 24; on the compressor bar 15. A crank 25 is secured tothe upper end of the rod 18.

From the construction of the parts just described, it will be seen thatrotation of the rod 18 in one direct-ion will cause the bar 15 todescend while a reverse rotation will cause the bar 15 to ascend.

interposed between the pads 12 and the compre .sor bar 15 are impedancecoils 26 and 27, the lower ends of which are secured to binding posts 28and 29.

The upper ends of the coils 26 and 27 are c nnected together, as at 30.The binding posts 28 and 29 extend through insulating bushings 33 asshown in section in Figure 2. They are supported by an car 34 extendingfrom each pad 12.

The connection is against the insulation 17, and clears the boss 24, asshown in dotted lines in Figure 1.

It will be seen that the coils 26 and 27 are completely insulated fromthe core 10.

It will be noted by referring to Figure 2, that the successive turns ofthe reactance coils and 2? are spaced farther from each other at thebottom of the coils than at the top. The purpose of this is so that asthe bar 15 is moved downwardly, the wire of the coils will begincontacting at the top of the coils and as the bar '15 de scends, thecontact portion will increase, thereby shorting more and more of theupper portion of the coils, consequently cutting down their reactanceuntil the coils are completely compressed and shorted and practically noresistance is encountered by the current passing therethrough.

In Figure 3, the portion from 35, up, is shorted and the reactanceencountered is the sum of the reactances in the two coils 9.6 and 27from 35 down.

it is apparentthat my device can be used in a great variety of circuitsand for all purposes. where a variable reactance is required. Forillustration, I have shown it in circuit with a motor in Figure 4.

The. feed wire 36 is connected to my impedance and a lead 37 connectsthe im pedance to the motor and thecircuit is i'zmnplete al through tlireal wire 39.

It a non-inductive resistance is required, the core 10 may be ofinsulating material, thereby eliminating the inductive effect of an ironcore.

It will be seen that I have provided a simple, variable resistance andan efiicient means for adjusting it.

I have eliminated the jumpy eilect of a rheostat having contacts whichare connected together by resistance units, and are thus adjustable bysteps. 1 have also entirely eliminated arcing contacts and theirdesctrnctive etlect.

For different requirements, finer wire or a greater quantit; may be usedfor designing the coils 26 and 27 for higher resistance. The pitch otthe threads 23 may vary for obtaining a coarser or liner adjustment perrevolution of the crank 25.

Some changes may he made in the construction and arrangement of thevarious parts of my invention. without departing from the real spiritand purpose of my invention, and it is my intention to cover by myclaim, any forms of structure or use of mechanical equivalents, whichmay he reasonably included Within its scope.

I claim as my invention:

An adjustable impedance coil comprising a core, a coil of resistancewire of uniform diameter wound thereon and having one end fixed relativethereto and the other end adapted to slide thereon, the pitch of saidcoil unitorml varying from end to end thereof, means for moving the freeend of said coil of resistance Wire alone said core whereby the adjacentturns of said coil are successively closed and the resistance of saidcoil unitormlv reduced.

MICHAS HENDERSON.

